This application is a participating center application for the first phase of the Cooperative Amblyopia Classification Study, a multi- center, planned, protocol based project to examine the existing clinical classification of amblyopia and compare it with a classification derived from the performance of the amblyopic eye on a set of specific psycho-physical tests. The data that emerge will be analyzed: - To determine a set of visual behaviors that distinguish amblyopic from normal eyes. - To determine clusters of visual behaviors that define different types of amblyopia. - To determine the correlation between types derived from psychophysical and oculomotor measures and clinical measures collected on the same patients. The statistical techniques of cluster analysis will be used on the measured clinical and psychophysical variables to examine the null hypothesis that the cluster of psychophysical measures can be predicted from the clinical classification and vice versa. The population studied will be amblyopic subjects, control subjects with clinical conditions usually associated with amblyopia but without the amblyopia and normal subjects. Ages range from 8 to 35 years. Full details of the project are contained in the Manual of procedure which accompanied the Lead Grant application.